Maple and Main Streets are straight and perpendicular to each other.

Maple and Main Streets are straight and perpendicular to each other. A stationary police car (the police car is not moving) is located on Main Street 1/4 of a mile from the intersection of the two streets. A sports car on Maple approaches the intersection at the rate of 50 miles per hour. How fast is the distance between the two cars decreasing when the sports car is 1 mile away from the intersection?